They are about 4 cm long in adults and more than a centimeter in diameter. The arteries run inferolaterally, along the medial border of the psoas muscles to their bifurcation at the pelvic brim, in front of the sacroiliac joints.

The common iliac artery, and all of its branches, exist as paired structures (that is to say, there is one on the left side and one on the right).